Known electrophotographic image forming apparatuses include, for example, laser printers and LED printers. A developing cartridge is used in such image forming apparatuses. The developing cartridge includes a developing roller for supplying toner. Some image forming apparatus includes a drawer unit. The drawer unit includes a photosensitive drum. In this case, a developing cartridge is attachable to the drawer unit. In response to attachment of the developing cartridge to the drawer unit, the photosensitive drum and the developing roller contact with each other.
Some developing cartridge is attachable to a drum cartridge. The drum cartridge includes a photosensitive drum. In response to attachment of the developing cartridge to the drum cartridge, the photosensitive drum and the developing roller contact with each other. The drum cartridge having the developing cartridge attached thereto is further attached to the image forming apparatus.
The image forming apparatus performs a separating operation as necessary. In the separating operation, the developing roller is separated from the photosensitive drum temporarily. For example, in a case that a color printer performs monochrome printing, developing rollers of developing cartridges for colors other than black are separated from the respective photosensitive drums in the separating operation. At that time, a position of a housing of each of the developing cartridges relative to the drawer unit or the drum cartridge is changed.
Some other known developing cartridge may include a storage medium. The storage medium may be, for example, an IC chip. The storage medium may include an electrical contact surface. The electrical contact surface of the storage medium may be configured to contact a terminal portion disposed at the image forming apparatus or at the drawer unit. Some further known developing cartridge may include an electrode. The electrode of the developing cartridge may receive electric power from the image forming apparatus. The electrode may also include an electrical contact surface. The electrical contact surface of the electrode may be configured to contact the electrode of the image forming apparatus or the drawer unit.
However, when the image forming apparatus performs the separating operation on the developing cartridge having the electrical contact surface, a relative positional relationship between the electrical contact surface and the terminal portion may be changed in accordance with the change of the housing of the developing cartridge. Therefore, every time the separating operation is performed, the electrical contact surface and the terminal portion may be rubbed against each other.